Last week I got an e-mail from Rob T. who found a spelling mistake on my “About Grammar Girl” page.

There’s a segment that reads like this:

Mignon believes that learning is fun, and the vast rules of grammar are wonderful fodder for lifelong study. She strives to be a friendly guide in the writing world. Her arch enemy is the evil Grammar Maven, who inspires terror in the untrained and is neither friendly nor helpful.

I had written arch enemy as two words, and Rob believed it should be one word, and when I started researching the spelling, I found a bunch of interesting things.

Archenemy Is Sometimes Capitalized

I first checked five dictionaries—Merriam-Webster, American Heritage, Dictionary.com, the Macmillan Dictionary, and the Collins Dictionary. They all spell it as one word, but some of them noted that it's often used to refer to the devil and when it is, it’s capitalized. I didn’t know that.

The First Citation for Archenemy Is From Myles Coverdale

Then I checked the Oxford English Dictionary because I wanted to see if the spelling had changed over time. Often a word will start out as two words and later merge into one word. That wasn’t exactly the case here. Arch-enemy was hyphenated in most older examples, but the oldest example—the first use of the word in 1550—was as one word, and it was from Coverdale!

You’re probably wondering who Coverdale was and why I’m so excited. Myles Coverdale compiled the first complete version of the Bible that was ever published in Modern English. It was also the first official printed version of the Bible in English in England. He built on the work of William Tyndale, who just a few years earlier had been put to death for translating the New Testament into English. Someday I’ll do a whole show about the history of Bible translations in the evolution of English because all the people who did them were influential, but the short story today is that Coverdale is a big name in the history of English, so I was excited when he popped up as the first person to ever use the word archenemy. Here’s the sentence:

He is the deadly archenmye of God, and of all mankynd.

So again, it’s one word and it’s referring to the devil, although it wasn’t capitalized in this example.

The Spelling Started to Change Around 1940

Finally, I did a Google Ngram search, which shows the instance of words and phrases in published books that Google has scanned, and that showed me something interesting: it looks as if there was a dramatic shift in spelling around 1940. Before 1940, the two-word version was more popular, but after 1940, the one-word option is more popular.

The shift is much more pronounced in American books than in British books. In American books, you see an obvious shift, whereas in British books the two spellings seem to converge in popularity around 1940 and are still in equal use today. I was wondering whether it had something to do with WWII, but it wasn’t really a dramatic increase in the use of the word archenemy, it was just a dramatic shift in how it was spelled. I couldn’t find a reason for the shift in spelling that only happened in American English, so I’m hoping one of you will know why the spelling changed. If you do, please leave a comment.

American Usage of Archenemy Versus Arch Enemy

British Usage of Archenemy Versus Arch Enemy

Until then, the bottom line is that Robert was right. Being an American, I definitely should have spelled it as one word. I’ve changed it on the website, and thank you for sending me down this interesting research rabbit hole.